Dynamical Electroweak Symmetry Breaking in String Models with D-branes

TL;DR

This paper explores a string theory-based model where dynamical electroweak symmetry breaking occurs via strong gauge interactions without elementary Higgs fields, analyzing a toy model with D-branes and supersymmetry breaking.

Contribution

It introduces a novel string-inspired framework for dynamical electroweak symmetry breaking using D-branes and analyzes a specific toy model with supersymmetry breaking effects.

Findings

Potential solution to the large S parameter problem via gauge kinetic mixing.

Identification of challenges in constructing realistic models.

Analysis of a supersymmetric D-brane orbifold setup.

Abstract

The possibility of dynamical electroweak symmetry breaking by strong coupling gauge interaction in models with D-branes in String Theory is examined. Instead of elementary scalar Higgs doublet fields, the gauge symmetry with strong coupling (technicolor) is introduced. As the first step of this direction, a toy model, which is not fully realistic, is concretely analyzed in some detail. The model consists of D-branes and anti-D-branes at orbifold singularities in (T^2 x T^2 x T^2)/Z_3 which preserves supersymmetry. Supersymmetry is broken through the brane supersymmetry breaking. It is pointed out that the problem of large S parameter in dynamical electroweak symmetry breaking scenario may be solved by natural existence of kinetic term mixings between hypercharge U(1) gauge boson and massive anomalous U(1) gauge bosons. The problems to be solved toward constructing more realistic models are clarified in the analysis.